High Adhesion and Increased Cell Death Contribute to Strong Biofilm Formation in Klebsiella pneumoniae.

Siddhi Desai,Devarshi Gajjar,Kinjal Sanghrajka

doi:10.3390/pathogens8040277

Siddhi Desai, Devarshi Gajjar + Show 1 more

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https://doi.org/10.3390/pathogens8040277

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Abstract

Klebsiella pneumoniae (Kp), is a frequent cause of hospital and community-acquired infections and WHO had declared it as a “priority pathogen”. Biofilm is a major virulence factor of Kp and yet the mechanism of strong biofilm formation in Kp is unclear. A key objective of the present study is to investigate the differences between strong and weak biofilms formed by clinical isolates of Kp on various catheters and in different media conditions and to identify constituents contributing to strong biofilm formation. Quantification of matrix components (extracellular DNA (eDNA), protein, exopolysaccharides (EPS), and bacterial cells), confocal laser scanning microscopy (CLSM), field emission gun scanning electron microscopy (FEG-SEM) and flow-cytometry analysis were performed to compare strong and weak biofilm matrix. Our results suggest increased biofilm formation on latex catheters compared to silicone and silicone-coated latex catheters. Higher amounts of eDNA, protein, EPS, and dead cells were observed in the strong biofilm of Kp. High adhesion capacity and cell death seem to play a major role in formation of strong Kp biofilms. The enhanced eDNA, EPS, and protein in the biofilm matrix appear as a consequence of increased cell death.

Highlights

Klebsiella pneumoniae (Kp) is the most common causative agent of nosocomial Gram-negative bacteremia and urinary tract infections (UTI) after E. coli [1,2]
The present study extends the knowledge about constituents contributing to strong
The biofilm index (Biofilm index = OD570(CV assay) /optical density (OD) 600(culture) ) and OD of bacterial culture after 24 h of biofilm formation, before washing of unbound cells was measured to validate that the difference in biofilm formation is not because of difference in the growth rate of the bacteria [23]

Summary

Introduction

Kp is the most common causative agent of nosocomial Gram-negative bacteremia and urinary tract infections (UTI) after E. coli [1,2]. Among Klebsiella spp., Kp is a prominent etiological agent of nosocomial and community acquired infections and has emerged as an “urgent threat” to public health due to multidrug resistance. Biofilms are a major issue in healthcare and are reported to be involved in. 65% of bacterial infections, allowing cells to persist and leading to increased antibiotic resistance [3]. Catheter-associated urinary tract infections (CAUTIs) by Kp represent one of the most common hospital-acquired infections (HAIs) leading to increased patient morbidity [6]. Bacterial biofilm formation on the interior and exterior surfaces of the catheter has been identified as the most important cause of CAUTIs [7]. Biofilm is an aggregate of microorganisms attached to an inert or living surface by a self-produced exo-polymeric matrix, which include polysaccharides, proteins, and extracellular

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